1. Field of the Invention
The present invention relates to an air conditioning apparatus for a rear seat of a vehicle, more particularly, relates to a blower unit having a centrifugal fan for the air conditioning apparatus.
2. Description of Related Art
A conventional air conditioning apparatus for a vehicle is described in JP-U-52-33850. In the conventional air conditioning apparatus, a sirocco fan 201 is disposed in a cylindrical case 200, as shown in FIG. 14. The sirocco fan 201 is a centrifugal multi-bladed fan having forward curved blades. Between an inner peripheral surface of the case 200 and an outer peripheral surface of the sirocco fan 201, a rotary door 202 is disposed to open and close an air outlet of the case 200. A scroll-shaped air passage 203 where a sectional area is gradually increased is formed between an inner peripheral surface of the rotary door 202 and the outer peripheral surface of the sirocco fan 201. A guide portion 204 is formed on the inner peripheral surface of the rotary door 202. In the conventional air conditioning apparatus, air-blowing energy generated by the sirocco fan 201 is changed from a dynamical-pressure component to a hydrostatic-pressure component by the guide portion 204, so that air-blowing pressure can be increased.
In the conventional air conditioning apparatus, a first opening portion 205 and a second opening portion 206 are respectively formed in the case 200, and an air outlet mode where air is simultaneously blown from both the first opening portion 205 and the second opening portion 206 can be set. Further, the conventional air conditioning apparatus is generally installed in a passenger compartment at a front side, and air is mainly blown from an instrument panel toward a rear side of the vehicle. Thus, in a one-box car having a large passenger compartment, air-conditioning feeling for a passenger seated on a rear seat in the passenger compartment is deteriorated. Therefore, an air conditioning unit for a rear seat in the passenger compartment may be provided. However, in this case, because a long duct is necessary to supply air to an air outlet for blowing air toward the rear seat, ventilation resistance is extremely large and the amount of air blown toward the rear seat in the passenger compartment is reduced.
Further, in the conventional air conditioning apparatus, because the sirocco fan 201 is used, the scroll shaped air passage 203 is necessary to increase the air-blowing pressure. However, since both the opening portions 205, 206 are formed, a complete scroll-shaped air passage cannot be formed relative to both the opening portions 205, 206. Thus, in the conventional air-conditioning apparatus, the pressure of air blown from both the opening portions 205, 206 is insufficient; and therefore, the amount of air blown from both opening portions 205, 206 becomes insufficient.